This application relates to blow molded containers and, more particularly, to blow molding appurtenances to a container.
The blow molding process is used to form hollow articles such as containers by expanding a parison extruded sleeve of heat softened plastic under pressure to match an inner contour of a mold. The mold is typically formed of first and second mold halves positioned together to define a mold cavity having a parting line between the mold halves. This process is used to form thin walled hollow products of uniform thickness. A parting line is present in the article formed from the parting line of the mold.
Blow mold tooling, particularly for large shipping containers, is relatively expensive. A significant portion of this cost can be attributed to the necessary appurtenances for the article. The appurtenances were previously limited to the parting line areas of the blow molded part. After a mold has been constructed and there arises a need for additional appurtenances to be added to the article, especially if the desired location is other than the parting line, it is either prohibitively expensive or not possible to add such appurtenances. As the mold halves pull away from each other at their parting line, any appurtenances which are not located at the parting line would capture the part in the mold. Because the mold generally has closely spaced cooling lines, it becomes prohibitively expensive or impossible to install retractable molding features through the ball of the mold, especially if those appurtenances are only to be added temporarily for a customized version of the standard molded part then removed later to again produce the standard part.
The present invention is directed to overcoming one or more of the problems discussed above in a novel and simple manner.
In accordance with the invention there is provided a blow molded article in which an appurtenance is integrally fused to a container during the blow molding of the container.
Broadly, there is disclosed herein a blow molded article comprising a hollow container of thermoplastic material defined by a continuous outer wall having a parting line formed during blow molding the container. An appurtenance of a material different from the thermoplastic material is integrally fused to the container during the blow molding of the container at a location of the container other than the parting line.
It is a feature of the invention that the appurtenance is heat fusion bonded to the outer wall.
It is another feature of the invention that the appurtenance comprises an injection molded plastic insert.
It is a further feature of the invention that the appurtenance is made of a stronger plastic than the thermoplastic material.
It is yet another feature of the invention that the appurtenance is made of metal.
It is still another feature of the invention that the appurtenance is made of a thermoplastic material.
In accordance with another aspect of the invention, there is disclosed a blow molded shipping container including a hollow bottle of thermoplastic material defined by a continuous outer wall having a parting line formed during blow molding the bottle and a fill opening located on the parting line. An appurtenance of a material different from the thermoplastic material is integrally fused to the bottle during the blow molding of the bottle at a location of the bottle other than the parting line.
It is a feature of the invention that the appurtenance comprises a threaded inlet opening.
It is yet another feature of the invention that the appurtenance comprises a tie down loop.
There is disclosed in accordance with a further aspect of the invention the method of manufacturing a blow molded shipping container comprising the steps of providing a mold having first and second mold halves positioned together to define a mold cavity having a parting line between the mold halves, removably fastening a preformed appurtenance to one of the mold halves at a location other than the parting line, expanding a parison extruded sleeve of heat softened plastic in the mold to conform to the mold cavity and to fuse around the appurtenance to securely heat bond the appurtenance to the plastic to form a shipping container, and removing the shipping container from the mold cavity with the appurtenance being released from the mold half.
It is a feature of the invention that the removably fastening step comprises fastening the appurtenance to the mold half using a magnet.
It is another feature of the invention that the removably fastening step comprises magnetically fastening a threaded holder to the mold half and threading the appurtenance to the threaded holder.
It is another feature of the invention that the removably fastening step comprises removably fastening the appurtenance to the mold half using a removable adhesive.
It is yet another feature of the invention that the removably fastening step comprises frictionally fastening the appurtenance to the mold half.
It is still another feature of the invention that the removably fastening step comprises fastening the appurtenance to the mold half using a releasable fastener.
In accordance with the invention, a pre-shaped insert or a temporary holder with the insert attached to it is temporarily attached to locations in the mold which are not at the parting line. These may be attached by some means such as removable adhesives, magnets, friction clips, etc. which would allow the insert attached to its temporary holder to be attached to the interior mold at any location, including locations away from the parting line of the mold while the parison extruded sleeve of heat softened plastic is expanded in the blow molding process and fused around the insert to securely heat fusion bond the insert to the wall of the blow molded shipping container.